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Venous lymphatic malformation


Imaging

  • Magnetic resonance imaging (MRI) has the unique ability to characterize hemorrhage using hemoglobin’s paramagnetic qualities and makes it ideally suited to evaluate VLM.

  • MRI clearly demonstrates the internal structure of subacute and chronic hemorrhagic cysts based on paramagnetic qualities.

  • MRI may detect “flow voids” from large feeding vessels not appreciated by computed tomography (CT).

Computed tomography features

  • A soft, bulky, nonencapsulated infiltrative tumor of mixed attenuation, full of ectatic channels containing clear fluid.

  • Poorly circumscribed soft tissue mass crossing anatomic boundaries of the conal fascia and orbital septum.

  • Enhancement ranges from patchy areas to the majority of the lesion.

  • Hemorrhages cause cystic regions with “rim-enhancement.”

  • Cystic components may both increase and decrease attenuation, contributing to fluid-fluid level (see Figure 31-1 , A ).

    FIGURE 31-1 ■, A, Axial CT shows a large retrobulbar intraconal/extraconal mass deforming the globe with exophthalmos. Conspicuous fluid-fluid level is evident, with heavier high-attenuation fluid inferior to lower attenuation fluid floating on top. B, Axial T1 shows a large complex retrobulbar mass causing exophthalmos. The mass surrounds and stretches without otherwise involving the ON. The mass shows increased T1 signal brighter than adjacent fat and clearly contains septations. C, Coronal T2 shows increased T2 signal in multiple cystic components of the mass OD. The mass clearly does not respect conventional anatomic boundaries. D, Coronal T1 fat-saturation shows an increased signal multiloculated right orbital mass, which does not suppress with fat. E and F, Coned axial T1 fat-saturation without (E) and with (F) Gd shows slight heterogeneous enhancement, which is somewhat difficult to appreciate because of the already increased T1 signal. G and H, AP and lateral arterial phase computed tomography angiography (CTA) shows no abnormal arterial blood supply, shunting or early venous filling of a high-attenuation multiloculated orbital mass that extends anteriorly and inferiorly. Clearly unencapsulated, the mass resembles a “glob” of silly putty.

  • An unencapsulated mass may resemble a “glob” of silly putty on CT (see Figure 31-1 , G and H ).

  • One half enlarge with Valsalva maneuver; ∼ one third contain phleboliths.

MRI features

  • MRI appearance is characteristically complex:

    • Increased T1 signal from methemoglobin (see Figure 31-1 , B ).

    • Increased T2 signal from fluid-filled spaces (see Figure 31-1 , C ).

    • Decreased T2 signal from deoxyhemoglobin or hemosiderin.

    • Post Gd enhancement is quite variable. Some do not enhance at all (see Figure 31-1 , E and F ).

    • May exhibit “rim-enhancement” around cysts.

    • Pure lymphatic cystic components are bright on T2. Hemorrhagic cysts have a variable signal based on stage.

  • Modality of choice for imaging VLM.

  • MRI provides dramatic differentiation of hemorrhagic cysts.

  • MRI has a unique knack for visualizing vascular flow voids from tumor vessels.

  • MRI comfortably shows bulky blood-containing cysts or tiny tortuous conduits.

  • MRI and magnetic resonance angiography (MRA) can comfortably separate slow-flow and high-flow vascular malformations.

Clinical issues

Presentation

  • VLM usually presents with gradually progressive proptosis (85%), ptosis, and decreased eye movements (50%).

  • Sometimes, spontaneous intraorbital hemorrhage causes proptosis, optic nerve (ON) compression, and visual loss.

  • Most subjects showed symptoms in the first or second decade, but occasionally symptoms were detected in tardy adults.

  • Female to male ratio = 2:1.

  • Fewer than 10% demonstrate diplopia.

  • VLMs enlarge as a response to viral infections.

Natural history

  • Solid VLMs are more amenable to resection. Cystic VLMs are more easily drained.

  • Regardless of the range of resection, recurrence is the norm so the need to preserve crucial structures usually outweighs the requirement for perfect resection. ,

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